36    boost::container::flat_set<T>& dst,
 
   37    boost::container::flat_set<T> 
const& src)
 
   42    dst.reserve(dst.size() + src.size());
 
   44        boost::container::ordered_unique_range_t{}, src.begin(), src.end());
 
 
void SetUnion(boost::container::flat_set< T > &dst, boost::container::flat_set< T > const &src)
Given two flat sets dst and src, compute dst = dst union src.